I've been trying to find a proxy server that will allow me to assign multiple outbound ips to a single client and use them in a round robin fashion.
For example:

ip 123.0.0.1 use ips in pool 63.0.0.2-63.0.0.254.

I can't seem to find one that will do this.

I understand how to setup Squid, but I have been told and from googling it's not possible to achieve this. If anyone knows of a proxy server that will do this I'd love to know. If I was told wrong and squid can do this please point me to a howto.